Online question and answer (Q&A) community web sites, for example, on the Internet can receive questions and retrieve answers in a variety of fields. Searching for similar questions in online question and answer (Q&A) community web sites for answers is a difficult task because different users may formulate the same question in a variety of ways, using different vocabulary and structure. For instance, the same question can be rephrased in many different ways and two questions may be different but may refer implicitly to a common problem with the same answer. Many Q&A community sites, however, advise users before posting a new question to search for similar questions.